1. Field of the Invention
The present invention is directed to making lenses on a wafer level, in particular to using wafer processing techniques to create a desired lens functioning, illustratively starting with substantially identical base lenses formed on a wafer level, and structures formed thereby.
2. Description of Related Art
Previous wafer level manufacturing techniques have assumed that the lenses made on the wafer level were identical within required parameters for their end use. As tighter tolerances ate required, this assumption may no longer be realistic. As the use of arrays of micro-optical lenses becomes more prevalent, differences between lenses therein may result in erroneous functioning. Further, many applications are now requiring the use of microlens arrays in which the microlenses therein have different properties, e.g., different focal lengths. Typically, such different arrays were created using different parameters for the underlying lenses themselves. However, it is easier to create a wafer of substantially identical microlenses than to try to adjust the parameters for individual microlenses thereon.
This creation of an array of different lenses is particularly difficult when the microlenses are to be refractive lenses created using reflow techniques. When etching reflowed lenses into a substrate, lenses having different radii of curvature require the chemistry used during etching to be altered at different points. Thus, the creation of an array of different reflowed refractive lenses on a wafer level becomes impractical.
The present invention is therefore directed to methods and structures which overcome at least one of the above disadvantages.
It is an object of the present invention to compensate and/or vary optical characteristics of an optical lens structure based on a substantially identical refractive surfaces created on the wafer level.
It is another object of the present invention to correct for variations in a refractive surfaces created on a wafer level from a desired functioning.
It is another object of the present invention to create an array of microlens structures having different optical characteristics based on an array of substantially identical refractive surfaces created on the wafer level.
At least one of the above and other objects may be realized by providing an array of micro-optical components includes at least two micro-optical components. Each micro-optical component includes a refractive surface and a corresponding compensation surface for the refractive surface. The corresponding compensation surface includes a corresponding compensation feature when the refractive surface deviates from a desired optical performance. The micro-optical component provides the desired optical performance. At least two refractive surfaces of the array of micro-optical components are formed to have substantially a same desired optical performance. The array of micro-optical components includes at least one corresponding compensation feature, at least two compensation surfaces of the array of micro-optical components being different from one another.
All combinations of refractive surfaces and corresponding compensation surface may operate at a same focal length or different combinations may operate at different focal lengths. The refractive surfaces and the corresponding compensation surfaces may be formed on a same substrate or on different substrates of at least two substrates bonded together. The corresponding compensation features may correct for aberrations in a corresponding refractive surface.
The corresponding compensation features may include a corresponding separation of the corresponding compensation surface from the refractive surface in accordance with a desired focal length of the combination of the refractive surface and the corresponding compensation surface. The corresponding separations may be formed in accordance with a measured focal length of a corresponding refractive surface.
The desired focal point of the micro-optical component may be on a back surface of a substrate on which the micro-optical components are formed or on a substrate bonded thereto.
The corresponding compensation features may include a diffractive element, which may correct for aberrations in a corresponding refractive surface.
At least one of the above and other objects may be realized by providing a method of forming micro-optical components having a desired optical performance. This includes creating a plurality of refractive surfaces on a substrate, providing a corresponding plurality of compensation surfaces, one for each refractive surface, measuring an optical performance of at least one refractive surface of the refractive surfaces, comparing measured optical performance with a desired optical performance, forming a compensation profile on a compensation surface when a corresponding refractive surface deviates from its desired optical performance, creating refractive surface-compensation surface pairs, each pair having its desired optical functioning; and separating the plurality of pairs into a desired number of micro-optical components.
The separating may create a plurality of pairs or may create at least one array of pairs.
The forming of compensation features may include forming compensation features on the substrate on which the plurality of refractive surfaces have been formed. The forming of compensation features may include forming the compensation features on a different substrate than the substrate on which the plurality of refractive surfaces have been formed, and bonding the substrate having the compensation features and the substrate having the plurality of refractive surfaces. The forming of compensation features may include etching the substrate in accordance with a desired focal length of the micro-optical component. The etching may result in different focal lengths for at least two of the micro-optical components. The forming of compensation features includes etching the substrate in accordance with a measured focal length of the corresponding refractive surface. The forming of compensation features may include etching using a single mask to simultaneous create a pattern for all of the compensation features. The forming of compensation features may include etching using a single mask to create a pattern for the compensation features, the single mask being moved to create the pattern for the compensation features. The forming of compensation features may include forming a diffractive element. The forming of compensation features may include creating at least two corresponding compensation features for different compensation surfaces that are different from one another.
A desired focal point of the micro-optical components may be on a back surface of a substrate on which said at least two refractive surfaces are formed or on a substrate bonded thereto.
The creating of the plurality of refractive surfaces may include using the same process for all of the refractive surfaces.
The measuring of optical performance may include measuring optical performance for each refractive. The measuring of optical performance may include measuring optical performance for a subset of the plurality of refractive surfaces.
These and other objects of the present invention will become more readily apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating the preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.